As for a conventional technique in regard to laser-clad processing, a laser-clad apparatus disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 9-155,583 has been known, for example. The laser-clad apparatus disclosed in the publication is, as shown in FIG. 25, one which is equipped with laser-beam irradiation means 50 for irradiating a laser beam L with respect to a process part W, a table T′ for holding a cylinder head, rotary driving means 51 for rotating the cylinder head held on this table T′ around the central axial line J of respective valve seats, and a table-position adjusting mechanism 52 for moving and adjusting the position of the table T′ so as to coincide the central axial line J of a valve seat to be processed with said predetermined rotary axis in an X- and Y-direction two-dimensional plane.
In such a conventional technique, as shown in FIG. 24, in order to inhibit a powdery material P, which is supplied in order to constitute a valve-seat surface, or a powdery material P, which is melted by the laser beam L, from running down into a valve hole or maldistributing, it is held on the table T′ in such a state that the central axial line J of the valve seat is inclined with respect to the vertical direction so that the process part W becomes upward, that is, so that the vertical line K with respect to the process part W directs in the absolute vertical direction. And, it is one which irradiates the laser beam L along the line K, which is vertical with respect to the process part W, in the vertical direction while rotating the cylinder head around the axial center line J. That is, it is a technique in which the laser beam is fixed but the cylinder head rotates to carry out laser-clad processing.
However, in such a conventional technique, in addition to inclining the entire cylinder head by a predetermined angle so that a part for forming the valve-seat surface becomes upward as shown in FIG. 24, it is necessary to move the entire cylinder head, a heavy-weight object, rotatably while adapting the central axial line J of the valve seat making the process part to the rotary center. In addition to firmly positioning and holding the cylinder head, such a heavy-weight object, in order to rotate this smoothly, a huge facility as shown in FIG. 25 becomes necessary so that a great deal of equipment investment and facility-installation space have been required.
Moreover, the powdery material, which has remained on the valve-seat portion without melting, has sputtered to the surrounding, because the cylinder head rotates, in actuality, however, its recovery is extremely difficult. Accordingly, the yield ratio of the powder material has degraded, and at the same time there has been a problem as well that the dissipated powder material becomes the cause of troubles at movable parts of the processing apparatus.
The present invention has been done in view of such circumstances, and it is an object to provide a laser-clad processing apparatus which can appropriately and readily form a clad layer at low cost with a simple constitution, and a laser-clad processing method therefor.